Image circle too large?

[Argentum]

well no becasue if image circle of lens A is 164mm(approx your fuji) and image circle of lens B is 108mm(approx your contax) and they are both same focal length at same aperture, then to get same image area on your film or digital back, then lens A will need to be further away than Lens B so for the same image captured you can't make a direct comparison about DoField which you are trying to do.
And you can not magically make lens A capture more light than lens B at same aperture so methinks your claim that DoField is different is probably becasue your subject distance is different for same image with the two lenses which obviously means doField will be different.

[Theodoros]

well no becasue if image circle of lens A is 164mm(approx your fuji) and image circle of lens B is 108mm(approx your contax) and they are both same focal length at same aperture, then to get same image area on your film or digital back, then lens A will need to be further away than Lens B so for the same image captured you can't make a direct comparison about DoField which you are trying to do.
And you can not magically make lens A capture more light than lens B at same aperture so methinks your claim that DoField is different is probably becasue your subject distance is different for same image with the two lenses which obviously means doField will be different.

Actually things are never so complicated... If you mount a (say 37x49) MFDB on the Fuji and then on the Contax, and focus them the same for the same scene, then the Fuji lens "sees" a wider angle than Contax (the sucks more -spits more case) and what is not recorded on the image area is lost... What you are left with is with two lenses, both recording the same AOV but see a different one and that supply the same through the same pipe "hole" (meaning the aperture) but the "hole" is in different distance from the image area... There is really no "magic" into it... Its simple physics... Theory presumes that lenses are symmetrical, they "see" the same AOV and are positioned in the same position... If one of the three doesn't apply, then theory doesn't apply... In this case ALL THREE don't apply...

[Dan Fromm]

I don't understand the question... my Fuji 210 never had any modification... why should it? Distribution of light is (supposed to be) even across image areas no matter the size of them... for equal image areas you get the same amount of light distributed despite the lens image circle, the rest is (supposed to be) lost or absorbed! (although it "passes" through the lens) So why modify it? ...The entrance pupil of the lens is positioned at a significantly larger distance from the image area and this causes DOF to be shallower...

cos^4, also known as optical vignetting, anyone?

[Jac@stafford.net]

I nominate a new forum category for absurdity and to name it Argentum vs. Theodoros, a pair or insignificant particles orbiting one another in a universe made of words rather than substances practical in the world of LF.

Done?
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[Dan Fromm]

You do sound like a "drunk"... or at least have the behavior of one... Never the less people forget that theory makes assumptions... and among the assumptions that it makes, is that lenses are symmetrical (and hence their entrance pupil is always at the mounting distance)... or ignores that (some) people drink too much! ...do you have a theory if the lens is one of retrofocus design though? ...Think of it after you are back and sober...

Dunning-Kruger, anyone?

[Jon Shiu]

Well, it doesn't make any sense for them to design a lightweight compact camera that can't use a 90mm lens. I looked on B&H and they say the lens can be 50-125mm, so it appears around 90mm lens would be good. So, I guess more research is in order. Perhaps there are different versions.

[Theodoros]

I think that if two lenses are mounted in different distance from the image area, then the proportion of image area to lens and lens to subject change (and thus DOF does) is far easier for one to understand...

[Argentum]

back on track

[Jac@stafford.net]

cos^4, also known as optical vignetting, anyone?

I thought you would never ask. I do happen to have a 3" Biogon that FAPP does defeat the very most of optical vignetting over 4x5", but to accomplish such it cheats by having a rear element larger than 4x5". Oh, on 8x10"? Don't ruin my day.

Call upon our theo/argen pair to put it through the mixmaster.
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[Jac@stafford.net]

Dunning-Kruger, anyone?

Well that Trumps everything.
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